This article is a very significant one by the author of two books I recommend, The God Instinct, and The Belief Instinct. He tells us: "Although Klüver-Bucy Syndrome is relatively rare, it's one of the most notorious neurological causes of a complete breakdown in one's ability to control sexual urges." Read both pages linked below and see what you think. Here is his conclusion:

What's the take-away message? I'll let you do the hard work of thinking through the implications for our belief in free will and how it might or might not apply. But another intriguing question emerges, too: If a "good" person's brain can be rendered morally disabled by an invasive tumor or an epileptic fuse-shortage, subsequently causing them to do very bad deeds, then isn't it rather hypocritical to assume that a "bad" person without brain injury—whose brain is anatomically organized by epigenetics (the complex interplay between genes and experiences)—has any more free will than the neuroclinical case? After all, perhaps it's just a matter of timing: The "good" are born with brains that can "go bad," whereas the "bad" are hogtied by a morally disabled neural architecture from the very start. And although it may be less common, if a "bad" person behaves in an upstanding manner, could that be the result of fortuitous brain damage or epilepsy, too?

It's all brain-based in the end, including the parameters by which one can contemplate and, especially, execute their free will. Perhaps we're only as free as our genes are pliable in the slosh of our developmental milieus.